Searches for invisible decays of the Higgs boson in pp collisions at sqrt(s) = 7, 8, and 13 TeV

TL;DR

This work combines CMS searches for invisible Higgs decays across ggH, VBF, and VH production channels using 7, 8, and 13 TeV LHC data, to constrain the Higgs branching fraction to invisible states. The analyses rely on MET recoiling against distinct visible systems (VBF jets, Z/H leptons, or hadronic jets) with data-driven background control regions and a joint likelihood fit. The result is a 95% CL upper limit of $\mathcal{B}(H\to inv) = 0.24$ under SM production, with interpretations in Higgs-portal DM scenarios yielding competitive DM-nucleon cross-section limits at low DM masses. This work strengthens constraints on invisible Higgs decays and provides improved tests of Higgs-portal DM models complementary to direct-detection experiments.

Abstract

Searches for invisible decays of the Higgs boson are presented. The data collected with the CMS detector at the LHC correspond to integrated luminosities of 5.1, 19.7, and 2.3 inverse femtobarns at centre-of-mass energies of 7, 8, and 13 TeV, respectively. The search channels target Higgs boson production via gluon fusion, vector boson fusion, and in association with a vector boson. Upper limits are placed on the branching fraction of the Higgs boson decay to invisible particles, as a function of the assumed production cross sections. The combination of all channels, assuming standard model production, yields an observed (expected) upper limit on the invisible branching fraction of 0.24 (0.23) at the 95% confidence level. The results are also interpreted in the context of Higgs-portal dark matter models.

Figures (13)

• Figure 1: Feynman diagrams for the three production processes targeted in the search for invisible Higgs boson decays: (upper left) ${q}\xspace{q}\xspace\to{q}\xspace{q}\xspace{H}\xspace$, (upper right) ${q}\xspace\overline{{q}}\xspace\xspace\to\mathrm{V}{H}\xspace$, and (bottom) ${g}\xspace{g}\xspace\to{g}\xspace{H}\xspace$.
• Figure 2: Feynman diagrams for the gg$\to$ZH production processes involving a coupling between (left) the top quark and the Higgs boson or (right) the Z and Higgs bosons.
• Figure 3: Distributions of (left) ${\Delta\eta(\mathrm{j_{1},j_{2}})}$ and (right) $m_{\mathrm{jj}}$ in events selected in the VBF analysis for data and simulation at 13$\,\text{Te\spaceV}$. The background yields are scaled to their post-fit values, with the total post-fit uncertainty represented as the black hatched area. The last bin contains the overflow events. The expected contribution from a Higgs boson with a mass of 125$\,\text{Ge\spaceV}$, produced with the SM cross section and decaying to invisible particles with 100% branching fraction, is overlaid.
• Figure 4: Distributions of $m_{\mathrm{T}}$ in data and simulation for events in the (left) 0-jet and (right) 1-jet categories of the ${Z}\xspace(\ell^+\ell^-)$ analysis at 13$\,\text{Te\spaceV}$, combining dielectron and dimuon events. The background yields are normalised to 2.3$\,\text{fb}^\text{$-$1}$. The shaded bands represent the total statistical and systematic uncertainties in the backgrounds. The horizontal bars on the data points represent the width of the bin centred at that point. The expectation from a Higgs boson with a mass of 125$\,\text{Ge\spaceV}$, from ZH production, decaying to invisible particles with a 100% branching fraction is shown in red.
• Figure 5: Distributions of $E_{\mathrm{T}}^{\text{miss}}\xspace$ in data and predicted background contributions in the (left) $\textrm{V}(\mathrm{jj})$ and (right) monojet channels at 13$\,\text{Te\spaceV}$. The background prediction is taken from a fit using only the control regions and the shaded bands represent the statistical and systematic uncertainties in the backgrounds after that fit. The horizontal bars on the data points represent the width of the bin centred at that point. The expectations from a Higgs boson with a mass of 125$\,\text{Ge\spaceV}$ decaying to invisible particles with a branching fraction of 100% are superimposed.